BP's Deepwater Horizon oil spill off the coast of Louisiana â?? and the company-led assault to contain it â?? isn't limited to the water. A less obvious twist to the nation's worst environmental disaster is drifting on the winds, suggesting tar balls aren't all Texas will see of the crisis. And while the oil must surrender to the shore, bad air knows no boundaries.

“It's the same from New Iberia, Louisiana, to Pensacola, Florida,” said Wilma Subra, hailed by CNN as “another Erin Brockovitch” and by the Guardian UK newspaper this week as possibly BP CEO Tony Hayward's “worst nightmare.” “When the wind comes out of the south and onto the land, people onshore have these health impacts.”

Though the EPA, which has been monitoring air quality across the coast with stationary and mobile labs, maintains that air pollutants from the spill do not pose a health hazard, agency scientists are turning up a variety of toxic constituents â?? just not at levels they see as problematic. Subra, however, describes hundreds of calls and conversations she has had with coastal residents who describe headaches, dizziness, nausea, and breathing trouble. “A lot of people are discussing with their families whether they should move out of the area,” she said, “particularly the vulnerable, the ones with small babies or babies that have respiratory problems.”

While the small tubful of petroleum goo washing up on far East Texas beaches inspired a sensational rash of headlines across the country, a recent westerly turn of the winds drew little notice. Yet it inspired Subra to suggest East Texas residents may start feeling an itch in their lungs much the way some of their neighbors in Louisiana have been for months.

When those tar balls rolled up on far East Texas beaches to be quickly bagged and tagged this July Fourth weekend, they were a touch lighter than when they originally gushed out of the maw of BP's Deepwater Horizon. Their lighter elements, trace gases like benzene and toluene, the stuff you may be breathing at the gas station as you convert your hard-earned capital into liquid energy, have long since turned to vapor and (most likely) blown landward.

While chemical components like benzene are known cancer causers, they probably have diluted in the atmosphere to such a degree that they wouldn't be measurable by the time they reach land, if they reach land, said Gunnar W. Schade, assistant professor of atmospheric sciences at A&M University. And yet there is very little we know about what is building up over the Gulf. “To gather more definitive data you need to go there,” Schade said.

So, for the past several days, a colleague of Schade's has hoisted a weather balloon over the site of the Deepwater spill collecting information about the chemistry of the Gulf air that will both help track the migrating toxics and assist in future weather-prediction efforts. The group expects the results to be far worse than the air quality that followed 1989's Exxon Valdez spill, where the cleanup didn't include large-scale burning or dispersant spreading.

Evaporation from the spill isn't the only source of hazardous air pollutants. Consider the toxic dispersants BP is still spraying on top of the slick against the EPA's instruction. Consider also the poisons rising from the burning oil and gas, now sending black smoke into the air around the clock. While Schade said he wouldn't expect to find much of the aeromatic hydrocarbons like benzene over land, he expressed concern about the chemicals being created by the burns.

The burning of the spill on the open water and by the Q4000, the oilfield construction vessel now collecting and burning oil and gas at the Deepwater site around the clock, creates extremely hazardous byproducts. Since the burning is happening so close to the water, the relative coolness of the water keeps the flames from destroying as much of the oil and gas as they would normally, most likely mutating rather than destroying a large amount of chemicals. The resulting chemicals are termed “products of incomplete combustion,” or PICs.

PICs produced would include highly carcinogenic chemicals, polycyclic aromatic hydrocarbons, or PAHs, according to Schade, which are known to damage human DNA and contribute to birth defects. “They are much worse than the typical straight-chain hydrocarbons,” Schade said. “You should definitely stay away from that smoke plume. â?¦ Anyone who is working out there is at much greater risk.”

That plume is 60 miles southeast of Grand Isle, Louisiana, and frequently blows toward land.

Across the coast, the EPA is using mobile labs and a chain or monitoring stations to keep tabs on what's in the air. To date, the agency is reporting that constituents like benzene and other aeromatic hydrocarbons have “been well below levels that would cause temporary discomfort, irritation, or other minor effects.” And while elements of the Corexit dispersant have been detected at many stations, they are so low as to pose only an “insignificant impact on air quality,” according to the EPA.

The most recent data available on the EPA website shows the air near Grand Isle had a constant level of xylene on July 2, with period spikes. While levels were below detection for benzee and toluene most of the day, there were frequent spikes. At one point, benzene was recorded at 6.2 parts per mbillion and toluene was measured at 9 parts per mbillion.

OSHA's short-term exposure limit for benzene exposure in the workplace is 5 ppm for benzene.

Air-quality-related questions sent to the EPA were not immediately returned.

Subra has been helping communities turn the tables on polluters for decades. In San Antonio, she has advised the Southwest Workers Union in their struggle to link area illness and disease to contamination from the old Kelly Air Force Base. In North Texas, Subra has assisted residents of Dish quantify the amount of toxic contamination being dumped on the town by natural gas drilling activities.

This morning she said that she is working with a couple attorneys that have been collecting their own air samples from the BP spill who are expected to release their data by the end of the week.

For now, however, she doesn't have any advice for those talking of relocating. “It's tough to say everybody should be out of here, or it's tough to say no one should leave, but constantly, constantly I'm getting calls that people are being made sick. The vulnerable ones are really the critical ones right now," she said. "Now the winds are moving everything to the west, toward Texas. It all depends on the winds, where it's carried. â?¦ I'm expecting to start hearing complaints from that area.”